As any tyranid player knows,  when building troop models you tend to accumulate Rippers. I found that I had a dozen of them. And it turns out that in 40k 9th edition (and now also in 10th)  Ripper Swarms have 4 wounds per base.

Three bases of Rippers. 

I decided to have each ripper count as a Wound token. So when the model takes a Wound, I remove an individual Ripper. I decided to accomplish this by using magnets on the bottom of the rippers with a sheet magnet on the base. The first few that I magnetized were stronger than the rest, so I will try to make sure I leave them towards the back of base to make it easier to move the model during play.

A strong magnet indeed 

Next came the basing materials. 

Grit and skulls. 

I added a few skulls to the bases and some grit. Trying to leave as much room as I could for the magnets to work of course. 

I started to basecoat these critters when I decided to take them with me to a game. Due to a lack of foresight on my part, some of my tyranid models were damaged by the heat when my car got too hot. One of these ripper bases was severely warped unfortunately, forcing me to re-do it. 

Yeah, there is no hope here. So I removed the skulls and removed the sheet magnet from the now useless base. It occurred to me while I was working on this, that I could use the number of skulls on the bases to denote the base number for easier cross reference to the roster. As I proceed on this project, that is what I am going to do. Let's see how far I get with these things in part 2.